In forms of lasers, pulse lasers for enabling intermittent light emission separately from a continuously oscillating continuous wave (CW) laser can significantly increase peak power and are used in various fields such as optical processing and non-linear optics.
In recent years, a mode-locked laser obtained by operating a semiconductor laser in the form of an external resonator has served as a master laser and a high peak power of a few hundred watts (Ws) has been reported in a so-called master oscillation power amplifier (MOPA) for amplifying an optical output of the master laser in a semiconductor optical amplifier (for example, see the following Non-Patent Literatures 1 and 2).